Defined Contribution Plan, Pension and Other Post-Retirement Benefit Plans - Fair Values of Pension Plan Assets by Asset Category and by Level (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	$ 74,366	$ 73,386
Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	332	623
U.S. large value
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	2,434	4,815
U.S. large growth
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	2,059	5,270
International blend
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	4,854	9,134
Emerging markets
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	1,603	3,093
Balanced
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	18,246	17,952
Government bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	24,917	10,240
Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	12,634	11,297
Other
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	3,217
U.S. property
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	4,070	10,962
Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	6,428	13,801
Level 1 | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	332	623
Level 1 | U.S. large value
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	2,434	4,815
Level 1 | U.S. large growth
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	2,059	5,270
Level 1 | International blend
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	0	0
Level 1 | Emerging markets
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	1,603	3,093
Level 1 | Balanced
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	0	0
Level 1 | Government bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	0	0
Level 1 | Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	0	0
Level 1 | Other
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	0
Level 1 | U.S. property
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	0	0
Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	63,868	48,623
Level 2 | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	0	0
Level 2 | U.S. large value
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	0	0
Level 2 | U.S. large growth
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	0	0
Level 2 | International blend
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	4,854	9,134
Level 2 | Emerging markets
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	0	0
Level 2 | Balanced
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	18,246	17,952
Level 2 | Government bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	24,917	10,240
Level 2 | Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	12,634	11,297
Level 2 | Other
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	3,217
Level 2 | U.S. property
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	0	0
Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	4,070	10,962	$ 10,153
Level 3 | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	0	0
Level 3 | U.S. large value
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	0	0
Level 3 | U.S. large growth
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	0	0
Level 3 | International blend
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	0	0
Level 3 | Emerging markets
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	0	0
Level 3 | Balanced
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	0	0
Level 3 | Government bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	0	0
Level 3 | Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	0	0
Level 3 | Other
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	0
Level 3 | U.S. property
Defined Benefit Plan Disclosure [Line Items]
Fair value of pension plans assets	$ 4,070	$ 10,962